The goals of this project are to determine how glucocorticoids, growth hormone and thyroid hormone integrate at the subcellular level to influence the metabolism of rat thymic (immature) and splenic (mature) lymphocytes. We will assess the influence of each hormone alone and incombination on the rates of protein and RNA synthesis and degradation. These studies will be conducted under conditions which, negate precursor pool problems and selectively block precursor reutilization. Furthermore we will assess the influence of glucocorticoids alone and in combination with thyroid and growth hormone on the regulation of specific lymphocyte RNases, DNases and proteases and determine whether any of these enzymes are responsible for the cell death response in these cells. Lastly we will determine how each hormone regulates the transcription and/or translation of the thymus cell specific enzyme terminal deoxyribonucleoside transferase. The studies should provide insight into the mechanisms of steroid induced cell death and steroid resistance and also assess the roles of thyroid and growth hormone in these processes.